The present invention relates to a metal gasket having sealing beads with different width and height for securely sealing around a hole, especially for an intermediate portion between cylinder bores.
In an internal combustion engine, an improvement has been made continuously to provide a light and high power engine. For example, a compression ratio of the engine may be increased, and a distance between the cylinder bores is made narrower. In case the distance between the cylinder bores is made narrow, the weight of the engine can be decreased. However, it may cause a sealing problem between the cylinder bores. Especially, it may be difficult to completely and securely seal the intermediate portion between the cylinder bores.
In U.S. Pat. No. 4,711,456, a sealing device for sealing around the cylinder bores includes beads around the cylinder bores, wherein the beads are joined at an intermediate portion between the cylinder bores.
In U.S. Pat. No. 5,344,165, a bead around a fluid hole is made to have different spring constant. Namely, a portion where a high tightening pressure is applied has a spring constant greater than a portion where a moderate tightening pressure is applied. The spring constant may be changed by changing the height, width or curvature of the bead.
In the prior art patents, the sealing beads may be joined at the intermediate portion between the cylinder bores, and the spring constant of the bead may be changed. However, no specific arrangement is made to securely seal around the cylinder bores for the engine with the narrow intermediate portion.
Accordingly, one object of the invention is to provide a metal gasket, which can seal properly for an engine with a narrow intermediate portion between the cylinder bores.
Another object of the invention is to provide a metal gasket as stated above, which can provide sufficient high surface pressure at the intermediate portion when the gasket is tightened.
A further object of the invention is to provide a metal gasket as stated above, which can be manufactured easily and economically.
Further objects and advantages of the invention will be apparent from the following description of the invention.